Prince George's County police are not naming the girl who was arrested because she is being charged as a juvenile, but they said the victim was Paxton Davis of Washington.

The Maryland girl is being charged as a juvenile. (Representational image)

An 11-year-old girl has been charged in Maryland with first-degree child abuse resulting in death after she allegedly assaulted a 1-year-old she was left to care for, police said.

Prince George's County police are not naming the girl who was arrested because she is being charged as a juvenile, but they said the victim was Paxton Davis of Washington.

The girl charged is being held at a juvenile detention facility, police said.

The mother of the boy had left him in the care of adult members of the 11-year-old's family at their Suitland, Maryland, home on Feb. 23, county police said. The family was friendly with Paxton's family and he had been to the home before, police said.

He spent the night "supervised correctly" with adults in the home, said Maj. Brian Reilly, commander of the Criminal Investigation Division for the Prince George's County police.

The next morning, the girl's mother left the house to run an errand and left Paxton alone in the care of her young daughter, Reilly said. That is when the assault occurred, police said.

Relatives of the 11-year-old returned home and found Paxton injured and called 911. He was rushed to Children's National Medical Center in Washington.

County police detectives responded to the hospital around 3:25 p.m. on Sunday for a report of an injured baby. The baby was suffering from severe upper body trauma and died on Thursday from the injuries, police said.

The 11-year-old girl has admitted to assaulting the boy during that period, but police declined to say if a weapon was used.

"I don't know what motive there would be in a situation like this for an 11-year-old to assault a 1-year-old," Reilly said. "There's no words. There's no reason for this to take place."

Citing the ongoing probe, Reilly would not say how long the 11-year-old was left alone with Paxton other than that it was "very brief."

Reilly said veteran detectives with Prince George's do not recall anyone as young as the suspect being charged out of the homicide unit with such a serious offense.

"We're really trying to deal with a very unique situation involving a juvenile," Reilly said.

In Maryland, children must be at least 13 years old to babysit another child without an adult. Reilly said the 11-year-old had not taken care of Paxton previously

In November, a 10-year-old Wisconsin girl was charged as an adult in the killing of an infant, according to a report from The Associated Press. The girl was a foster child living at a home that also served as a day care. The girl dropped a baby who was at the day care and stomped on the crying child's head, the AP report said.

In 2010, an 11-year-old girl in Georgia was charged with murder after a 2-year-old in her care died, according to local news reports. The child charged in that case was the daughter of a co-worker with whom the victim's mother had entrusted her toddler, news reports said.

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)